1. Field of the Invention
This invention relates to a novel carbon black-graft polymer, a method for the production thereof, and use thereof. More particularly, this invention relates to a carbon black-graft polymer produced by the reaction of a polymer possessing a specific reactive group with carbon black and useful in toner for developing electrostatically charged images, resin composition, coating composition, ink for thermographic transfer, coating agent for thermographic transfer ink ribbon, back-coating agent for magnetic recording medium, rubber composition, and carbon black dispersion, a method for the production of the polymer, and use thereof.
2. Description of the Prior Art
Carbon black excels in coloring property, electroconductivity, weatherability, chemical resistance, etc. and, because of these features, has been finding extensive utility in various applications as reinforcing agents and fillers for plastics and elastomers. Since carbon black by nature comes in powdery or granular form, it is rarely used by itself. It is enabled to manifest the characteristic features thereof by being uniformly dispersed in a solid substance such as rubber or resin or in a liquid such as water or solvent.
The affinity of carbon black for other substances such as organic macromolecular compound, water, and organic solvent is weak as compared with the cohesive force generated between the particles of carbon black. It is extremely difficult, therefore, for carbon black to be uniformly mixed with or dispersed in other substances under ordinary mixing or dispersing conditions.
For the solution of this problem, many methods are being studied which are directed to enabling carbon black to be uniformly mixed with or dispersed in a solid or liquid substrate by coating the surface of carbon black with a varying surfactant or resin thereby enhancing the affinity of carbon black for the substrate.
Particularly, the carbon black-graft polymer which is obtained by polymerizing a polymerizable monomer in the presence of carbon black has been attracting attention because the hydrophilicity and/or oleophilicity thereof can be sitably varied by suitably selecting the kind of the polymerizable monomer.
Methods for the production of the carbon black-graft polymer are disclosed in Japanese Patent Publications SHO 42(1967)-22,047, SHO 44(1969)-3,826, and SHO 45(1970)-17,284, and U.S. Pat. No. 3,557,040, for example. These methods, however, produce carbon black-graft polymer of their species in low yields falling on the order of several to ten-odd percent. Most of these products occur in the form of vinyl type homopolymers and betray very poor efficiency of the surface treatment given to carbon black. The methods, therefore, have not improved the affinity of carbon black for other substances so much as are expected. Frequently, the conditions in which these products are dispersed in substrates are varied by mixing or dispersing conditions.
An object of this invention, therefore, is to provide a novel carbon black-graft polymer, a method for the production thereof, and use therof.
Another object of this invention is to provide a carbon black-graft polymer useful in toner for developing electrostatically charged images, resin composition, coating composition, ink for thermographic transfer, coating agent for thermographic transfer ink ribbon, back-coating agent for magnetic recording medium, rubber composition, and carbon black dispersion, a method for the production of the polymer, and use thereof.